Management and Prevention of Complications in Stapes Surgery and Ossicular Chain Reconstruction
Surgery for ossicular chain reconstruction and stapes surgery begins with the proper approach. In general, we recommend the endaural approach for stapes surgery. Some other centers (especially in the United States) prefer the transcanal approach. In ossicular chain reconstruction surgery the most appropriate approach depends on the pathology. For cholesteatoma surgery or operations that include the mastoid area, the postauricular approach is recommended because this allows comfortable control of the mastoid, the skull base, or the internal auditory canal.1 In cases of tympanic membrane perforations close to the anterior anulus, the postauricular approach allows better visualization of the operation site.
In general, the otologic surgeon should consider that surgery of the middle ear is “landmark” surgery. Important anatomical structures, such as Henle spine, the round window niche, the oval niche, and the facial nerve, need to be identified and inspected. One of the most consistent anatomic landmarks is the round window niche, which serves as the first anatomical orientation in revision surgeries.
In our department, the majority of middle ear surgeries are performed under general anesthetic. However, the standard application of local anesthesia ~ 15 to 20 minutes before surgery is mandatory to reduce intraoperative bleeding. Many other centers prefer local anesthesia for the entire surgery. Usually 3 to 4 mL local anesthesia containing a mixture of 2% xylocaine with 1:200,000 epinephrine is injected postauricularly and into all four quadrants of the external auditory canal. This should be done before disinfection to allow the local anesthesia time to take effect.2 In addition, it is particularly important to inject the anterior part of the external auditory canal when performing stapes surgery.
If unexpected intraoperative diffuse bleeding should occur, irrigation with physiologic solutions is recommended. For continuous bleeding, application of 0.5 mL of pure epinephrine solution (1:1,000) for several minutes is recommended. Especially in stapes surgery, an almost bloodless operative field is mandatory for a successful outcome. However, epinephrine should only be applied before the footplate is opened.
Tips for Middle Ear Surgery
Preoperative planning of the appropriate approach is mandatory to facilitate surgery and prevent complications.
Proper positioning of the patient′s head (supine, open angle) allows comfortable surgical dissection.
Visualization of important anatomical landmarks is essential for safe surgery
A standardized and proper local anesthesia technique is mandatory.
Intraoperative application of undiluted epinephrine 1:1,000 allows profound reduction of bleeding.
Stapes surgery requires precise surgical skills that come with experience. It is better to refer the patient to a specialist than to perform only the occasional stapes surgery. Table 3.1 summarizes the management of complications in stapes surgery.
Intraoperative Challenges and Complications
Minimizing complications in stapes surgery starts with the correct approach. In Europe most surgeons prefer the endaural incision over the transcanal approach.3,4 We usually perform the endaural incision using a middlesized speculum, a No. 10 blade for the intercartilaginous incision, and a No. 15 blade for lifting the meatal skin flap. The tympanomeatal flap should not be too short because a short flap length may not allow sufficient coverage of the curetted lateral attic wall, particularly if extensive drilling of the scutum in a far posteriorly located footplate is required. In these cases we perform an underlay tympanoplasty using a small piece of fascia.5
Tympanic Membrane Perforation
Tympanic membrane perforation in stapes surgery may occur during the elevation of the anulus. This can happen when an inexperienced surgeon slides over the anulus rather than elevating it from its bony sulcus. However, a tympanic membrane perforation is not considered to be a major complication. If it occurs, an underlay myringoplasty using temporalis fascia or tragal perichondrium is recommended, and these grafts can be harvested using the same approach. However, it is important to harvest the graft before continuing with the stapes surgery and opening the footplate.
Chorda Tympani Lesion
There are several steps during stapes surgery when the chorda tympani nerve may be injured. First, it can be damaged during the elevation of the anulus in the region where the nerve enters its bony canal. Second, the nerve may be injured during the curettage of the scutum. For a complete mobilization of the nerve it is also important to discontinue its attachment to the manubrium.6 The nerve should be preserved whenever possible; however, if maximum mobilization of the nerve does not allow sufficient exposure of the oval window, the nerve should be transected rather than extensively stretched.7 Several studies have shown that chorda tympani lesions do not lead to permanent taste disturbances in the majority of patients.8
Luxation of Incus
A luxation of the incus can occur during the removal of the lateral attic wall using a curette. The luxation can be into an anterior direction when the curette unintentionally slips toward the lenticular process or into a posterior direction when the curette slips toward the short process of the incus.5 To avoid this complication, we recommend the following technique for removal of the scutum.4 In a right ear the surgeon should use the left hand and rotate the curette counterclockwise ( Fig. 3.1 ). In a left ear the surgeon should use the right hand and rotate the curette in a clockwise direction ( Fig. 3.2 ). The curettage of the scutum should be continued until the insertion of the stapedius tendon into the pyramidal process can be seen. If the bone of this area is very thick, we prefer using the diamond drill to reduce the scutum ( Fig. 3.3 ).
Fracture of Lenticular Process
Fracture of the lenticular process may occur during the separation of the incudostapedial joint, fixation of the prosthesis, or removal of the scutum. It is usually possible to fix the prosthesis in more proximal regions of the lenticular process. If this is not possible a malleovestibulopexy may be needed.
Persistent Stapedial Artery
A persistent stapedial artery running through the stapes crura may obscure the view to the oval window ( Fig. 3.4 ). This has been reported to occur in 1 of 1,000 ear surgeries.9 Schuknecht10 recommends removing the stapes suprastructure and placing the artery anteriorly, which allows a safe insertion of the prosthesis. If this maneuver does not allow adequate exposure to the oval window, then discontinuation of the surgery is recommended by some authors.3 As recommended by others, we perform coagulation of the artery if the oval window is obscured.4,11
Narrowed Oval Niche
A thick bony promontory wall may cause a profoundly narrowed oval niche. In these cases, the bony area can be removed using a fine diamond bur at low rotation speed after the stapes suprastructure is removed. It is important to perform this technique before the footplate is opened.12 Sometimes an abnormal low-running or dehiscent facial nerve can partially or completely occlude the view to the oval window. In most cases of a partially occluded oval window, insertion of the prosthesis is still possible ( Fig. 3.5 ). If the oval window is completely blocked, some authors recommend termination of the surgery.13 In our department, a windowing of the promontory is performed.3 Häusler3 reported on 39 patients with stapedectomies and abnormal positioning of the facial nerve, and in 82% of these patients a postoperative conductive hearing loss of less than 20 dB was achieved. There was no case of facial palsy or deafness after surgery.
In cases of an obliterative footplate with broad thickening of the footplate, a fine diamond bur (e.g., Skeeter drill) is used for perforation of the footplate to achieve a small opening to the vestibule ( Fig. 3.6 ). The incidence of obliterative otosclerosis ranges between 1 and 16%.5
A free-floating footplate is a serious intraoperative event during stapes surgery. It describes a completely mobile footplate, which may occur during the perforation of the footplate, especially when the footplate has a “biscuit-type” thickening of the middle part. If a floating footplate occurs, we recommend drilling a small perforation on the promontory side of the vestibule using a fine diamond bur (0.6 mm) and carefully lifting and removing the footplate using a small hook.14 If all or part of the footplate is displaced into the vestibule, it is best to leave it there. If such is the case, we recommend covering the footplate with connective tissue and discontinuing the stapes surgery. If parts of the footplate are fractured, a small hook is inserted into the posterior portion of the footplate and the fractured piece is carefully pulled out.
Another intraoperative condition is the “gusher” phenomenon, which describes an intense and massive flow of perilymph/cerebrospinal fluid after perforation of the footplate. A patent cochlear aqueduct is believed to cause this phenomenon, and it is more often seen in patients with inner ear anomalies.11 There are more reports of a gusher on the left side than on the right.15 In cases of a heavy gusher, the surgery should be discontinued and a “waterproof” closure of the oval window should be made using fat or connective tissue. The “oozer” is a milder gusher and can often be controlled by the quick insertion of the prosthesis and sealing with connective tissue. In cases of a more extensive discharge of cerebrospinal fluid, a lumbar drain can help to reduce the pressure of the cerebrospinal fluid.16
The distance between the lenticular process and the footplate varies between 3.9 and 5 mm. In most cases, we use a 4.5-mm prosthesis. A prosthesis that is too long may come into contact with the utricle or saccule, which can cause profound vertigo and tinnitus. The tip of the prosthesis should not penetrate more than 0.5 mm into the vestibule.
Immediate Postoperative Complications
Immediate postoperative vertigo can be caused by a loss of perilymph, mechanically induced irritation of the inner ear, or a serous labyrinthitis.3 Symptoms usually subside after a few days. If inner ear damage is suspected, an application of high-dose corticosteroids (250 to 1,000 mg intravenous prednisone once daily on three consecutive days) is recommended.17 Loosening of the packing of the ear canal may also improve the symptoms.
Vertigo combined with fluctuating hearing can be a characteristic sign of a perilymphatic fistula. If a fistula is suspected, immediate revision and closure of the oval window by connective tissue should be performed. Progressing sensorineural hearing loss and persistent vertigo despite conservative therapy (high-dose corticosteroids and antibiotics) also necessitate an immediate surgical revision.18 For early detection of these complications, it is necessary to perform continuous examination of the patient using the glasses of Frenzel and a tuning fork. In cases of immediate revision with removal of the prosthesis, revision surgery for hearing improvement can be performed after 6 months.
To prevent inflammation of the auricular canal and tympanic membrane the patient has to be advised not to wear hearing aids for at least 1 week before surgery. In cases of an infection with herpes simplex or other infection of the upper airway, stapes surgery should be postponed.19
Hearing loss is considered to be the most serious complication after stapes surgery. Most authors estimate the risk at 1%, but there is wide variation in the incidence of this complication in different studies.3 In most cases the reason for postoperative deafness is unclear.20 Some surgical methods that pose an increased risk for the inner ear and subsequent hearing loss have been abandoned (e.g., coverage of the oval niche with Gelfoam, which was accompanied by an increased risk of inner ear fistulas21). If an inner ear complication is suspected, then high-dose therapy with corticosteroids as well as antibiotics should be initiated.17 In addition, before surgery, patients should be informed about the alternative treatment of hearing aid fitting.